Science Sunday; Parasites

What do parasites do?

Parasites suppress the immune system of the host in order to help them survive. They want to carry out their own life cycle and if they cause immunosupression to the host they are less likely to be killed. However, it is a trade off between the host dieing and the parasite being dieing. Parasitism is when an organism lives off another organism, it will be draining its resources.

Types of parasites

There are a number of different types of parasites. Helminths are worms that live in the host. They are often large and need to be well adapted to evade the host’s immune response to prevent them from being killed. They may also adopt host proteins as its own surface protein so it is not recognised as foreign by the immune system. Many have a long life cycle so it is in their interest to keep the host alive for a long time.  Helminths are a big problem in livestock and they are often put on worming programs. There are many different types such as strongyles that live in the intestines. 

Protozoa are small and will often live inside cells. An example of this type of parasite in the horse is Equine Protozoal Myeloencephalitis (EPM). 

Arthropods live on the outside of the animal such as ticks and fleas. They feed off the host through their skin. The well adapted ones have an anaesthetic in their saliva so the host will not feel them drinking their blood and will not scratch them off.

Strongyles vulgaris can be seen in the horse becomes infected by ingesting the larvae. They go through the small intestine and large intestine walls and get into the arteries 7 days after they have been infected. They then carry on developing for the next 3-4 months. Mature worms lay eggs which pass to faeces and pasture.

TreatmentsIvermectin is in the macrolytic class of wormers and is approved for the control of stomach bots, threadworms, pinworms, adult cyathostomes, adult and some larvae small strongyles and adult hairworms. It interferes with the brain in the parasite. There are a number of other types of treatments which can be used. There are problems with resistance developing to these wormers so they should not be over-used as this can increase resistance developing. 
There are also a number of other methods to control parasites which I will go into in another Science Sunday post. 



Love Laura
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Science Sunday; My Dissertation, Wormer Effects

After finishing the taught section to my masters course in June I completed a dissertation over the summer which was handed in at the end of November. My dissertation was looking into the effects wormers may have on the bacteria that live in the hindgut of the horse. These microbes are important as they carry out some of the digestion of the food the horses eat, helping the horse to get more nutrients. You can read more about this in my digestive system post. My first dissertation which I carried out in my final year of my undergraduate degree was also looking at changes in the hindgut bacteria of horses but this was looking at the effects of probiotics, click here to read about it. This has given me quite a good understanding of this area of the horse.

What I did
At the start of the study faecal egg counts were carried out for a number of horses, the results of this led to the two groups that were in my study. If the horses had a high enough burden of worms to be treated they were in the "treated" group and if they were not treated they were in the "control" group.

I then took poo samples on three separate occasions and analysed the DNA of the microbes present in these in the lab. This showed me which species of bacteria were present under the different conditions and how they may have changed.

What I found
I found there was a difference in the bacteria living in the hindgut of the horse between the two groups of horses. However, that difference seemed to be there from the beginning of the study which suggested to me that the presence of worms in the digestive tract of the horse may have causes these differences. I concluded that more research is still needed as my sample size was only small (it contained 12 horses) but the results were interesting and a good starting point for further research.

Love Laura
xxxx

Guest Post; Where's Your Tack Tonight?

Today I have a guest post from Easy2Insure, an independent insurance broker with access to a variety of horsebox policies providing insurance for all types of horseboxes including motorised horseboxes and trailers.  Visit us their website to find out more about their horsebox insurance that's right for you, your horse and your budget.

Whether you’re at a show or at home, there’s always a chance that thieves could strike without warning. With rural crime on the rise, even being out in the countryside is no guarantee that your tack room and everything in it is safe. So do you know where your tack is tonight? Let’s look at tack security at home and away.

Why is tack a target?

In the modern age anything that isn’t nailed down (and even some things that are!) is a potential target for thieves. Because tack is high value and easily transportable (you can quite literally carry it away), it is becoming a favourite target for thieves. Tack is also reasonably generic, and it can be very difficult to prove ownership of a standard saddle, for example, unless it has some particular distinguishing marks. So it’s easy to sell on without ‘too many questions’ being asked…

There are two types of thieves – opportunist thieves who will see an unattended item and simply grab it, and more organised gangs who may plan the robbery beforehand. Opportunistic thieves are more likely to strike at shows and events, while the more organised (and often more dangerous) gangs target remote locations such as livery stables, yards and farms.

Home security

This is probably the easiest to scenario to deal with, as there is much more you can do to protect your tack and possessions at home than when you’re at a show.

Locks – It may seem obvious, but even if your nearest neighbour is five miles away, fit a lock to your tack-room door. Make sure those locks are strong enough to withstand a sustained and determined attack by a thief.

Alarms – Silent alarms are probably the most effective, as they will activate a secondary alarm in your property, allowing you to contact the Police while the thieves are still in situ, thus giving them a better chance of catching the thieves ‘in the act’.

Cameras – Security systems that include motion-sensitive cameras are now very reasonably priced and make a worthwhile investment, particularly if your tack is expensive, custom-made or professional standard.

Insurance – Even large items such as horse boxes can be at risk, so make sure you have horse box insurance. This will also often cover any tack that is stored in the box, and give you some peace of mind that you won’t be facing a big bill if things go missing!

Geese! – One of the best alarm systems you can have is couple of geese living in the yard (the geese at a yard we used to ride in would attack anyone who wasn’t wearing riding boots!).

At a show

Security at a show is much more complicated, as there will be times when your tack is left unattended, even for a brief moment while you dash to the tea hut! This is where opportunist thieves strike, so make life difficult for them.

Lock it up – If you’re lucky enough to have a horse box with a lockable tack storage area, then make sure you use it! Again, as with home locks, choose padlocks that are going to give thieves a problem (circular padlocks are much harder to open using bolt cutters than traditional style padlocks).

Mark your tack – this won’t prevent it from being stolen, but if you use security markers to mark your tack then it may ensure that it gets back to you if the Police recover it later. Make sure you have a photographic record of all tack, especially saddles.

Don’t leave tack in plain sight – In the same way that you wouldn’t leave your handbag on the passenger seat of your car, try not to leave high-ticket items in plain sight. Remove the temptation and you lessen the chances of being a victim of theft.

Insurance on the go – Check with your specialist insurance broker to see if your horse box insurance covers your tack whilst at a show. Again, it won’t stop your tack being stolen, but it will make it financially much easier to replace!

Science Sunday; Sarcoids

Sarcoids are the most common form of skin tumour in the horse. They are often seen on the head, and they may be a problem if near the eye. They are also seen on the lower body, limbs and sites of previous injury. Trooper has a small sarcoid in between his front legs and has had it for a few years without having any problems from it.

Types of sarcoids

There are six types that occur. 

• Occult has hair loss and they are often on the neck. 
• Verrucous are wart like, cytokines transform the epidermis. 
• A fibroblastic legion is the most ugly, they are red and weep. They are often seen on the pastern or the upper eyelid. 
• The nodular form is where there is intact skin over them, the skin will move over them, this means they are easily removed with surgery. They are often seen around the eye or the inguinal region. 
• They can be a mixed form.
• They can also be a malignant form, this is not common.

 Treatments

The treatment options currently available for sarcoids in the equine are limited. Surgical excision can be done. However, this may cuase recurrence and may enhance the growth. Some nodules may be OK to be removed in this way. Cyrosurgery may be done, this is when the tissue is frozen, mixed results have been seen using this method. This may cause scarring however and should not be done near the eye. Immunotherapy can be used such as using a vaccine, this would need to be given in a series of injections.This triggers an immune response and will help to heal it. However some horses are allergic to this. Radiotherapy can be used, this is more modern. Gold, radium and iridium are used and inserted into the legion. Topical chemotherapy may be used. There is a risk to the handler when using this as it is unstable. The smaller the sarcoid the easier to treat so it has to be done early.  This method has been used for around 200 years. 

Cause

The cause of sarcoids is not known. However, it is currently thought to be a bovine papilloma virus (BPV) related virus. It is also suspected that there is a genetic predisposition but then there has to be a trigger. Younger horses, ages 2- 6 show the highest prevalence. Most studies have not found a breed or sex linked predisposition. Though it has been linked with castration wounds in geldings. Mohammed et al (1994) found an increased prevalence in arabs and quarter horses compared to thoroughbreds. It is thought it could be carried by flies as it is more common around wound areas. This may explain the geographical variations that are seen with sarcoids.

Love Laura
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Keeping Older Horses Supple

A lot of people have been asking me recently how I keep Trooper supple and prevent him from getting stiff. For those of you that don't know, Trooper is 23 years old and had a tendon injury just over a year ago. He no longer jumps but I school him and he still goes nicely and can do lateral work and is not too on the fore-hand. The only thing he does do is trip up a bit.

Nutrition
People have been asking me if he is on any extra supplements to help prevent him from getting stiff but he only has Happy Hoof and sometimes Winergy Ventilate in his feeds. They were asking about glucosamine and chondroitins. Our dog is on glucosamine tablets and they are meant to be quite a cheap option for horses. Cortaflex is the one of these feeds that I have heard the most from, this contains both glucosamine and chondroitin. These are meant to increase the synthesis of joint cartilage so in theory help with things such as arthritis. However, in horses more research is still needed, especially into the dosage of these products.  Codlivine is another product given, some people do not like feeding this as it is an animal product. It is hard to tell what effects these have though in each individual horse and it may be more beneficial to give them a try if you are wondering and see how your specific horse reacts to them. I would be interested to hear if any of you have tried any of these products and how you have found them! Maybe in the future we will try out some of these products and report back!

Exercise
I think the main thing that is keeping Trooper supple is the amount we exercise him. We try to ride him at least 3 times a week and he is turned out every day for at least 6 hours even through the winter. When he had his tendon injury we still turned him out as we thought keeping him on box rest may lead to him stiffening up. When I ride him I warm him up for a good 5-10 minutes and then he goes really nicely. I think he does get a bit more stiff when he has not been ridden as often.

Also I have now found a way to add more photos into my blog after the Picasa storage ran out. For those of you wondering I have uploaded the photo to Flickr. I then went onto the "share" setting and got the HTML code for the photo. I then went onto the HTML button whilst writing a blog post and copy and pasted it into there! There might be other ways to do it but this is the way I have found! At least I can keep uploading photos for free! The photo below is a bit of a random one to go with this post but it wouldn't upload the other day so I thought I would try it here!

Love Laura
xxxx

Science Sunday; Why Are Foals Susceptible To Diseases?

New born foals are particularly susceptible to disease as they rely on colostrum from the mare to give them antibodies. Colostrum is the first bit of milk they get from their mother and is important as it contains antibodies developed by the mare that are a response to the immediate environment. The mare therefore has to be in the environment that the foal will be born into 2-3 weeks before so that the antibodies made will be specific to the correct environment. These antibodies allow the foal to fight infection before its immune system becomes efficient. The new born foal is able to absorb these antibodies through the intestinal wall and into the blood stream. The ability to absorb these antibodies only lasts for the about 12 -24 hours. During this period the foal needs to have 1- 2 litres of colostrums. These antibodies protect the foal for the first 2-4 months of life. After this, the foals own immune system becomes more efficient making its own antibodies. If the mare leaks colostrum, it will be lost so there will not be enough for the foal.

A number of conditions in the foal are a consequence of them not receiving enough colostrum, leading to a failure of them receiving this early immunity. This could be due to the foal being born premature or the mare running colostrum before parturition. There could be a reduced quality of colostrums that contains low antibody levels. The foals access to colostrum could also be reduced, such as the foal being separated from the mare of the foal being too weak to feed in the early hours after birth. The foals immunity levels and the quality of the colostrums can be checked in a number of ways to see if there are any problems.

These problems could be prevented by giving the foal colostrum supplementation, this is useful within the first 24 hours of birth. There are a number of types of antibodies and if it is given after this time the IgM antibody will still be absorbed but the IgG may not be. It may be possible to create a colostrum bank by milking the colostrum from a number of different mares after the foal ahs had enough, this can be stored in the freezer and mixed together and can be given to sick foals when they need it.

A plasma transfusion may be given if there are severe problems, this is when 3-4 litres of blood is taken from a donor mare or gelding. The plasma is separated from the blood. This can then be transfused into a foal and will raise their IgG antibody levels.

Love Laura
xxxx

Little Update

I'll start off this post with a quick story about Trooper from earlier this week. As he is out in the field during the day, he is always at the gate waiting for us when we go to the farm around 2:30/3:00 pm. Earlier in the week around 1 pm one of the grooms at the farm saw the gate to the field was wide open. She went up and she couldn't see Trooper anywhere! When she went onto the farm she could see Joe's bucket had been moved into the yard. Trooper usually heads straight for this bucket when he escapes. Joe's stable had been messed up and some of his hay-net had been eaten but Trooper had gone. She then looked over to the small shelter area where the haylage is kept and could see the back of Trooper's bum. He had gone right inside and had been eating from the huge, round haylage bale for a while as the mud had dried on his legs from when he left the field so had a nice feast. I think he will be heading straight there next time he escapes! We're not sure how he got the gate unlocked. He does barge the gate but it has a chain hooked round it. Either someone left this open or he barged it and it came off!

And just a little update to say I am currently trying to sort out a technical issue with uploading photos so I may not be posting as often as I like to include photos. I have reached the memory limit on my Picasa storage and have to may to increase the storage amount so I thought while I may have to may anyway I might be able to host my blog on my own website so I am just looking into the pros and cons of this at the moment. It might also help with the problems I have been having with people commenting.

Love Laura
xxxx

Science Sunday; Respiratory Disease

In the past I have talked about recurrent airway obstruction, this post is going to focus on other respiratory diseases.

There are a number of defence mechanisms in nose, airways and lungs (respiratory tract) in order to try and prevent diseases taking hold of this system. There are mechanisms that filter the air and throw the air around in the air in order to trap bacteria or viruses that may be entering through the nose. There are also other mechanisms such as the cough reflex and there are tiny hairs in the tract called cilia that waft mucus up the the airways away from the lungs carrying any foreign particles with it. If bacteria does reach the lungs there are also cells there called macrophages that eat them up to stop them causing problems.

Viral infections
Viruses can be spread by direct and indirect contact. After horses have been infected by a virus they may also be infected by bacteria as it will take the opportunity to attack while the immune system is low. A virus can damage cilia (the hairs that waft mucus up the airways) and this leads to mucus staying in the airways and not being removed

Horses are often diagnosed by the clinical signs and the history. Sometimes swabs may be taken within 48-72 hours. After 72 hours the virus may be isolated in the blood so blood tests can be taken. I will now talk about a few viral diseases.

• Equine influenza can be spread by direct contact. It is incubated in the horse for 1-3 days before symptoms may be seen. The virus will be shred for 10 days. Vaccines are difficult as there are many different strains and it can mutate, there are however vaccines that cab be given that cover a number of different strains. It is under global surveillance. The clinical signs are a high temp, depression, anorexia, nasal discharge, dry cough, and enlarged lymph nodes. Horses are rested for at least 4 weeks to allow the airways to regenerate. They are kept in a dust-free environment. 
• Equine herpes virus has 2 strains. Equine herpes virus 1 (EHV1) can cause abortion and neurological disease and is contagious. EHV4 is a respiratory disease and is occasionally contagious. It is spread by direct contact and horses show problems in 3-6 days. Horses will have a high temp, depression, serious nasal discharge and a mild cough. Again they are treated with rest but vaccinations don't work for this virus as yet. Horses should be isolated for 21 days and kept unstressed.

Bacterial infections

• Strangles is also called streptococcus equi, it can survive in water for 1-2 months. It can be diagnosed with nasal swabs but repeat sampling may be necessary as they need 3 negatives before they get the all clear. It causes fever, anorexia, nasal discharge, enlarged lymph nodes and other complications. It mainly affects horses aged 1-5 years and has an incubation period of 7-12 days. Carrier horses may not show symptoms but may pass it on to other horses. Antibiotics cab be given but may not work well. After coming into contact with the disease they are immune for up to 4 years.
• Rhodococcal infection in foals causes pneumonia. It is usually chronic, they get a high temp, cough, nasal discharge, increased heart rate and breathing rate, enlarged joints, diarrhoea and nervous system problems. This happens due to the immature immune system in foals. They may be diagnosed by clinical history, blood tests and ultrasounds. Vaccinations may be given.

Other respiratory diseases

• Parasites can cause infections in the lungs. This is uncommon but may happen in the late summer or autumn. Dictyocaulus arnfield is an example of this and may be carried by donkeys.
• Allergies may also be a problem. Recurrent Airways Obstruction (RAO) is an example of this, I have previously written a post on this which is linked at the top of this one. 

Love Laura
xxxx